In order to carry out certain operations of drilling and riveting on an aircraft fuselage, a guiding device is positioned temporarily on the outer surface of the fuselage in order to guide a tool in a direction of work.
According to an embodiment of the prior art shown in FIGS. 1 and 2, a guiding device 10 comprises:                a rail 12 which is configured to support a tool, and is deformed in order to extend in a first direction parallel to the direction of work of the tool;        a plurality of suckers 14 which are regularly distributed in the first direction, and are each configured to be secured temporarily on a surface;        for each sucker 14, a rigid sucker/rail connection 16 between the sucker 14 and the rail 12.        
Conventionally, an aircraft fuselage comprises a plurality of sections which are placed end-to-end at transverse planes, and each have an outer surface. When the operation carried out takes place in a direction of work parallel to a transverse plane of the aircraft, the guiding device 10 then follows the profile of a surface which has a radius of curvature in the first direction.
However, certain sections of fuselage have surfaces which are said to be non-developable. Some of these non-developable surfaces have a double radius of curvature, and in particular have a first radius in a direction parallel to a transverse plane of the aircraft, and a second radius of curvature in a second direction perpendicular to a transverse plane of the aircraft.
When the guiding device 10 is positioned on a section of fuselage with a non-developable surface, it matches the forms of the surface, and naturally tends to be distanced relative to the direction of work which the tool must follow. Thus, a first end of the guiding device 10 is arranged in the vicinity of the direction of work, whereas the second end of the guiding device 10 is distanced from the direction of work. For certain sections of fuselage, the distance between the second end of the guiding device 10 and the direction of work which the tool must follow is too great to be compensated for by the dimensions of the tool. In addition, because of this distance, the rail 12 can have torsion which blocks the displacement of the tool along the rail, and the guiding device 10 can interfere with other elements positioned around the fuselage.
In a case of this type of a section of fuselage which has a non-developable surface, the guiding device 10 cannot be positioned parallel to a transverse plane, since, in this position, not all of the surface of the suckers is in contact with the surface of the fuselage 18.
As illustrated in FIG. 2, only an end 14.1 of each sucker is in contact with the surface of the fuselage 18, the other end 14.2 being distanced.